electron-browser-storage/index.js

Access localStorage and sessionStorage from the main process

const { app, BrowserWindow } = require('electron');

// Create an empty BrowserWindow to access browser storage
let storageWindow;
if (app.isReady()) {
  initWindow();
} else {
  app.on('ready', initWindow);
}

// Initializes the storageWindow
function initWindow() {
  storageWindow = new BrowserWindow({
    show: false,
    webPreferences: {
      nodeIntegration: false,
    },
  });

  storageWindow.loadFile(__filename);

  // If this is the last window, user probably wants to quit. Closing this
  // hidden window will allow the app to quit.
  setInterval(closeIfLastWindow, 1000);
}

// Closes the storage window if it's the last one
function closeIfLastWindow() {
  const browserWindows = BrowserWindow.getAllWindows();

  if (browserWindows.length === 1 && browserWindows[0] === storageWindow) {
    storageWindow.close();
  }
}

// Executes code in the BrowserWindow
function execute(code) {
  if (!app.isReady()) {
    throw Error('Storage methods can only be called after the app is ready.')
  }

  if (!storageWindow) {
    throw Error('Storage window is not initialized.')
  }

  return storageWindow.webContents.executeJavaScript(code);
}

function Storage(storageName) {
  /**
   * Returns the number of items in the storage
   */
  this.length = () => execute(`window.${storageName}.length;`);

  /**
   * Returns the key at the given index
   * @param {number} index Index to get
   */
  this.key = index => execute(`window.${storageName}.key('${index}');`);

  /**
   * Returns the value for the given key
   * @param {string} key Key to get
   */
  this.getItem = key => execute(`window.${storageName}.getItem('${key}');`);

  /**
   * Sets the value for the given key
   * @param {string} key Key to set
   * @param {*} value Value to set
   */
  this.setItem = (key, value) => execute(`window.${storageName}.setItem('${key}', '${value}');`);

  /**
   * Removes the item at the given key
   * @param {string} key Key to remove
   */
  this.removeItem = key => execute(`window.${storageName}.removeItem('${key}');`);

  /**
   * Removes all keys and values
   */
  this.clear = () => execute(`window.${storageName}.clear();`);
}

/**
 * localStorage object
 */
module.exports.localStorage = new Storage('localStorage');

/**
 * sessionStorage object
 */
module.exports.sessionStorage = new Storage('sessionStorage');